The CPJ has raised concern about the case of Abu Zir al-Amin, the deputy editor of the suspended opposition daily Rai al-Shaab who was due for release after serving a prison sentence since May 2010.

But the prison authorities informed him that he would not be released as scheduled. Instead, he is being transferred to the custody of state security prosecution to face a further investigation.

He was arrested along with two colleagues for reporting that members of Iran's revolutionary guards had set up a weapons factory in Khartoum to supply arms to Hamas militants and Somali Islamist insurgents.

Al-Amin was then charged with "undermining the constitution," "terrorism and espionage," "publishing false news," "undermining the prestige of the state" and "inciting sedition."

He was originally sentenced to five years in prison but that sentence was commuted to one year by an appeals court earlier this year.

"We are profoundly disturbed by the audacity and spurious nature of the charges levelled against Abu Zir al-Amin," said the CPJ's Middle East and North Africa programme coordinator Mohamed Abdel Dayem.

It is alleged that Al-Amin was tortured during his imprisonment. A picture of him showing evidence of torture was leaked and appeared on several online outlets.

Another reporter, Jaafar al-Subki Ibrahim of the private daily Al-Sahafah, has been held incommunicado and without charge since November 2010.

According to the CPJ report, Sudan routinely targets privately owned and opposition newspapers with pre-printing censorship and confiscation of copies in order to prevent publication of contents that are deemed anti-government.